I can't imagine a withdrawal for amphetamine outside the come-down from a multi-day binge. The come-down lasts a day or two. Maybe a week of fogginess if you hit it fear-and-loathing hard.

If you're taking amphetamine at such a rate that you would call it a "withdrawal", then you might want to consider the possibility that you were abusing amphetamine.

It's common to double-dose on the weekend whether for a productivity spree or recreation (they're usually one in the same) even if you haven't taken a pill in months. You just have to pay a day or two penalty and you're good to go.